Slack adjuster for brakes



y 26, L. F. BROWN SLACK ADJUSTER FOR BRAKES Filed March 24, 1941ZuiZenZBfizwa ATTO R N EYS similar causes.

in brake applying position.

Patented Ma 26, 1942 UNITED STATES PATENT OFFICE' 2,283,966 SLACKADJUSTER FoR BRAKES Luther F. Brown, Amarillo, Tex. Application March24, 1941, SerialNo. 385,014 -2 Claims. (cuss-202) My invention relatesto slack adjusters for brakes and has as one of the principal objectsthereof the provision of a slack adjuster or device so constructed andarranged as to automatically take up excessive slack, incident, forexample, to wear of the brake shoes or other An important object of myinvention is to provide a device of the character described which issimple in construction, durable in use, efficient in operation andeconomical in manufacture.

Other'objects and advantages will be apparent from the followingdescription, appended claims and annexed drawing.

Referring to the drawing wherein like reference'characters designatelike parts throughout the several views;

Figure 1 is a plan view of my invention, partly in section.

Figure 2 is a view similar to Figure 1," but illustrating the piston rodand'associated parts Figure 3 is a sectional View taken on the line 3-3of Figure 2.

Figure 4 is a detail sectional view of the upper portion of the housingand illustrating the pawl in non-operating position with respect to theratchet wheel.

Figure 5 is a. view similar to Figure 4 and illustrating the pawl inposition for effecting rotation of the ratchet wheel for effectingequalization .of the brakes.

Figure 6 is a detail perspective view of the lower end of the bar foroperating the arms between which the pawl is pivoted.

.In practising my invention, as illustrated in the drawing, I employ abrake cylinder 5, equipped with the usual piston (not shown) to which isattached a piston ,rod 6 extending without said cylinder and pivoted toone end of a front lever l as at 8. The opposite end of the lever I ispivotally connected, as at 9, to the rear end of a brake actuating rod Iconnected to a pair of front brake shoes (not shown) for operating theshoes into and out of engagement with a pair of front wheels (not shown)A rear brake lever II is disposed rearwardly of the cylinder and has oneend pivotally connected, as at I2, to a frame member l3 of the vehicle.The opposite end of the lever II is pivotally connected, as at M, to thefront end of a rearwardly extending brake actuating rod IS, the latterbeing engageable with a pair of rear shoes (not shown) for operatingsaid shoes into and out of engagement with a pair of rear wheels '(notshown).

The front lever 1 is pivotally connected, be-

tween its ends, to the front of a sectional housing l5, formed with alongitudinal bore I! in which is disposed thefront threaded end of asectional tie-rod I8, the rear end of the latter being pivotallyconnected with the lever II as at l9. The housing 16 is fashioned with acentrally disposed recess 20 in which is mounted a worm gear Zlthreadedon the threaded end of said tie-rod l8. Also disposed in the recess is aworm 22 meshing with the worm gear 20, said worm being fixed to ashaft23 having its ends disposed in bearings 24 contained in the housing andwith said shaft extending at right angles with respect to the tie-rodl8.

One end of said shaft 23, adjacent the worm 22 has loosely mountedthereon a pair of spaced arms-25 extending upwardly through a slot 26formed in said housing and with the upper end of said arms pivotallyconnected to the lower end of a bar 2! as at 28. The arms 25 havepivotally mounted therebetween a gravity operated pawl29 for engagementwith a ratchet wheel 30'fixed to the shaft 23 between said arms asclearly illustrated in the drawing.

Adjacent the rearwardly disposed end of the slot 26, the housing I6 isformed with an upwardly extending portion constituting a stop 30' for'engagement with the arms 25. The arms 25 are connected .to the front endof a coil spring 3|, the rear end of which is attached to theupperiendof. a bracket32. The spring serves to urge the arms toward thestop 30. The lower end of the bracket 32 is secured to-the rear end ofthe housing in fixed relation therewith.

The upper end of the bar 2'! is pivotally connected tothe rear end of alink 33, the front end of which is pivotally connected to the lever 1adjacent its upper end as at 34. The lower end of the bar 27 extends atan appreciable distance beyond the pivot 28 and is fashioned withlaterally extending lugs 35 constituting a stop for engagement with theupper ends of the arms 25 p for a purpose hereinafter set forth.

cessively, the piston might travel out until it struck the head and thecylinder before the shoes would contact the wheels. For the foregoingreason, it is desirable to maintain the travel of the piston as uniformas possible, which inmost cases is approximately 8 inches. If

the travel of the piston belessthan the prescribed stroke, the shoes areapt to,.be 'maintained too close to the wheels, while if greater thanthis,'a small amount of extra wear of the shoes will allow the piston tostrike the head.

worm jo'urnalled in the housing and meshing with the worm gear, the saidworm having a shaft extension, a ratchet wheel fixed on the shaftextension of the worm, a pair of arms pivotally con- Therefore, when thepiston rod 6 is actuated outwardly, and one'setof theshoes engages thelugs 35 of .the bar 21 to engage the arms .25 and rotate the latter asufficient distance to ratchet wheels in advance of the other set, itcauses the the pawl 29 .over the ratchet wheel 30 to efiect engagementwith other teeth thereon, whereby when said piston rod 6 is actuated inthe oppo site direction, the ratchet wheel 30 will rotate" the shaft 23and'effect rotation of ithe*gear.,2il1

through the medium of the worm 2.2. ,When

, the gear 2i is rotated, it serves to advance the" front end of thetie-rodl8 intoj thehousingji ,1 thereby taking up the slack between thebrak shoes and wheels to effect simultaneous appli'cation' of all thebrake shoes ontheir' respective wheels upon operation of the brakecylinder- 'piston to brake applying position. Without furtherelaboration the so fully explain the invention that others may,

by applying current knowledge, readily, adaptt he same for use undervarious conditions of service.

Moreover, it is not indispensablethatjpallthefeaa tures of theinvention. be used conjointly sincethey maybe employed advantageously invarious combinations and sub-combinations. f r

It is. obviousthat the invention is not confined to the herein describeduse therefor-asit maybe utilized for any purpose to whichitis adaptable;

It is therefore to be understood that the invention-is not limited tothe specificv construction as illustrated and described as the sameis,only foregoing will movementof thelatter, a worm joumalled in the nectedto the said shaft extension and extending radially therefromat each sideof the ratchet wheel, a pawl pivotally mounted between the said arms inengagement with the ratchet wheel, 'a spring connected to the said armsfor yieldingly holding the pawl in a predetermined position, alink-pivotallyIponnected-to one of the said brake levers, and ,a barpivotally connected to the outer .end of the link and having knee 'jointconnection "with the said radial arms operative to move the ;pawl :onlyupon excessive movement of the said brakelever ior'slack takeup of thetie rod through j the action' ofthe spring and gear mechanism.

2,;iInji'a,v device. of the character described, a

c piston act ated brake lever, a second lever spaced 20 from the'pistonactuated lever, a housing piv- V otally connected to thesaid pistonactuated lever,

atierod pivotally connected to thesecond leverhaving theouter portionexteriorly screw threaded'and, slidablyassociated with the said housing,a worm gear Iotataloly mounted in the housing having ansinteriorlythreaded bore engaging the threaded portion of the tie'rod for.longitudinal housing andin-meshwith the said worm'gear,

the ;said worm having a shaft extension, a ratchet wheel {fixedtransversely on the shaft, extension at the,worm,;;a, pair :of arms:pivotally connected with theshaftextnsion and extending radiallytherefrom at each side oftheiratchetwheel, the

saidhousing having a stop projection for limitingthemovementof the saidarmsin one direction,

illustrative of the principles of operation, which are capable ofextended application invarious forms, and that the inventioncomprehends; all construction within claims. t

, WhatI claim is:;. i

1. In slack adjusting mechanism for vehicle brakes, a pair of spacedbrake actuating levers, operating means pivotally connected with one ofe the said levers, a housing pivotally 'connectedwith' the intermediateportion of one of the levers, a

the scope of the appended tie rod pivotally connected to theintermediate portion of the complementary lever having a threaded endportion telescopically engaging, the said housing, a worm gear rotatablymounted in the housing having an interiorly threadedbore engaging thethreaded portion of the tie rod, a

a pawl pivotally connected to the said arms engaging the ratchet wheel,a tension spring having connection with the housing and with the saidarmsyieldingly-holding the arms-against the stop projection, a link;pivotally connectedto the piston actuated brake lever, a bar connectedto thesaid linkaandpivotally connected to the pawl carrying arms, and anextension at the inner 1 end of .the bar engageable with the said armand

